There is conventionally known a manipulation apparatus, for example, as described in Patent literature 1. The manipulation apparatus in Patent literature 1 includes a rotary switch which partly projects from the upper surface of the casing and is rotated by a manipulator, and a rotation detection mechanism for detecting the rotation state of the rotary switch. A display unit is installed adjacent to the rotary switch; when a rotating manipulation is made to the rotary switch, the numerical value displayed on the display unit changes or the display content changes according to the rotating manipulation.